What are 2 ways that exposed rock can be weathered?
1. Mechanically
• Example: waves on a cliff
2. Chemical
• Example: rusting
What is bedrock? Why is it important to soil formation?• Bedrock: igneous, metamorphic, and
sedimentary rock of lithosphere that may exist as mountains, cliffs, or low-lying plains
• Supplies material needed to build soil
Describe what soil is and how is formed. • Soil: mixture of mineral particles, air,
H2O, & living and decaying organisms
1. Outer layer of bedrock weathers (cracks and holes)
2. Cracks reach deeper & outer layer becomes broken into small particles
– Burrowing animals & plant roots break down bedrock & aerate soil
VOCAB: parent
rock
Describe what a soil profile is and what 4 distinct layers form. • Soil profile: a vertical cross section of soil
from the ground surface down to the bedrock
• A Horizon: topsoil
• B Horizon: subsoil
• C Horizon: parent rock
• R Horizon: bedrock
Describe the 3 major soil textures.
1. Sandy: enables soil to drain well but dries out quickly; largest mineral size
2. Clay: flat and traps H2O, preventing H2O drainage; smallest mineral size
3. Loam: mixture of sizes for good drainage and moisture for plants; medium mineral size
Describe the interaction of soil & climate.
• Desert: small soil profile; large particles
• Grasslands: thicker soil profile; faster weathering of rock
• Tropical: very thick soil profile; very fragile soil because of so much rain; a lot of clay in the subsoil
What causes soil loss & desertification? What % has undergone desertification?
• Overgrazing, deforestation, & poor irrigation and cultivation
• 30%
How much topsoil is lost to water & wind erosion?
• 2.5 billion tons lost to water
• 1.5 billion tons lost to wind
• TOTAL=4 billion metric tons!
Describe the 4 types of soil conservation & land management.1. Strip-cropping: farmland plowed so
plowed strips separated by planted strips
2. Contour Farming: plowing along a slope instead of across it; furrows collect H2O which reduces erosion
3. Terracing: series of platforms (terraces) are built into the slope; separated by vertical steps
4. Shelter belts: rows of trees planted along outer edges of field
How do we define solid wastes?
• All garbage, refuse, & sludge products from agriculture, forestry, mining, and municipalities–Examples: garbage trash
junk sewage scrap refuse
Describe how garbage disposal has changed over the years. • Hunter-gatherers: left it and moved on
• Athens, Greece 500BCE: trashed dumped outside of city walls– Rest of Europe dumped in the streets
• NYC/NJ 1892-1900CE: garbage loaded onto ships and dumped in Atlantic Ocean
• Now we use landfills
What is a landfill? How much garbage is dumped there?
• Site where wastes are disposed of by burying them
• 70%
Why are open landfills no longer allowed in the US?
• It supported large populations of rats, insects, etc.
• Foul odor and disease
Describe what a sanitary landfill is & identify 2 problems.• Wastes are spread in layers ~3m deep &
compacted by bulldozers
• Soil spread on top of refuse & compacted
• Repeated until garbage reaches certain heights
1. Methane produced
2. Leaching of toxic substances
What are hazardous wastes?
• Solid, liquid, or gaseous wastes that are potentially harmful to humans and environment
• Love Canal, NY: Town built next to old chemical plant– Steel containers holding waste leaked– Birth defects and cancer affected the people– Government relocated them ($190 million)
Name 6 types of hazardous waste.
1. Reactive Waste: can explode 2. Corrosive Waste: can eat through steel,
clothing, and burn skin3. Ignitable Waste: can burn at low temp;
toxic fumes when lit4. Toxic Waste: chemicals that are poisonous
to people5. Radioactive Waste: gives off radiation
(given off when mining Uranium)6. Medical Waste: old medicine, medicine
containers, lab equipment and specimens
Identify & explain 4 methods for reducing volume of waste.
1. Recycle: paper, plastic, aluminum, glass, etc.
2. Reuse: cloth diapers
3. Biodegradable: leaves, grass clippings, food waste*, composting
4. Repair: old appliances, shoes, cars
Name 6 ways of disposing of hazardous waste.1. Waste exchange: use haz. waste in
production of other materials
2. Deep Well Injection: inject waste into porous rock under water table; LIQUID
3. Secure Chem. Landfill: waste is stored on nonporous bedrock
• pipes to monitor and collect leaks; cover with clay
4. Controlled Incineration: burn waste at high temp
• Expensive
5. Biological and Chemical Treatment Plants: turn harmful things into harmless
6. Radioactive Waste Disposal: put in H2O or bury underground
Briefly describe Superfund.
• Law designed to protect communities from dangers of hazardous wastes
• CERCLA (1980): got $9 billion dollars to implement